It is a common expedient in membrane chemistry to extract proteins, glycoproteins, lipoproteins, polysaccharides or lipopolysaccharides from membranes or organisms by treatment with a surfactant. No satisfactory methods have been available heretofore, however, for the detection, quantitation and separation of the extracting surfactants from the proteins or polysaccharides, particularly extremely low levels of surfactants. Most of the prior art procedures are spectrophotometric. Most of them lack sensitivity below 5 .mu.g and most of them can give false results due to interference by lipids, other type surfactants and proteins. None of them is applicable to all of the surfactants commonly used in membrane chemistry, i.e., one uses a different procedure with each surfactant.